SURVEY OF CANADIAN NEURO-ONCOLOGY CLINICIANS ABOUT THE TREATMENT OF ADULT MEDULLOBLASTOMA

Given the rarity of adult medulloblastoma, the optimal chemotherapy strategy is unknown and its management is thought to vary from institution to institution. Guidelines often omit suggestions for specific chemotherapy regimens, reflecting the lack of high-quality evidence in this population. We sought to understand Canadian adult medulloblastoma practice patterns, hoping to inform future quality metrics and guidelines. METHODS: In March 2022, a 30-question survey was sent out to 71 adult neuro-oncology clinicians on the Canadian Adolescent and Young Adult national rounds mailing list. Snowball sampling was permitted. RESULTS: The response rate was 35%. Radiation oncologists (11), neuro-oncologists (8), medical oncologists (4), and neurosurgeons (2) responded from 6/10 Canadian provinces. They each treated on average 1.6 medulloblastoma patients per year. Most (61%) said that molecular subgrouping was always done at their centre. Half indicated that cerebrospinal fluid testing was always done at diagnosis. The most common (64%) radiation regimen was 36 Gy (in 20 fractions) craniospinal irradiation + 18 Gy (in 10 fractions) boost. Concomitant chemotherapy was rarely given while adjuvant chemotherapy was frequently administered. The most common adjuvant chemotherapy was Cisplatin/Lomustine/Vincristine (57%), but other regimens included Cisplatin/ Lomustine/ Vincristine alternating with Cyclophosphamide/ Vincristine (21%), Cisplatin/ Cyclophosphamide/ Vincristine (14%), and carboplatin-based regimens (14%). Respondents noted challenges prescribing chemotherapy in this population: drug toxicities, limited resources, and clinical uncertainty. There was support for standard-of-care adult medulloblastoma guidelines in 92%. CONCLUSIONS: There is significant practice variation among Canadian neuro-oncology centres treating adult medulloblastoma. This variation can serve as an opportunity for quality improvement and clinical research.